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| -rw-r--r-- | Documentation/devicetree/bindings/mux/gpio-mux.txt | 69 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/mux/mux-controller.txt | 157 | ||||
| -rw-r--r-- | MAINTAINERS | 6 | ||||
| -rw-r--r-- | include/dt-bindings/mux/mux.h | 16 |
4 files changed, 248 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/mux/gpio-mux.txt b/Documentation/devicetree/bindings/mux/gpio-mux.txt new file mode 100644 index 000000000000..b8f746344d80 --- /dev/null +++ b/Documentation/devicetree/bindings/mux/gpio-mux.txt @@ -0,0 +1,69 @@ +GPIO-based multiplexer controller bindings + +Define what GPIO pins are used to control a multiplexer. Or several +multiplexers, if the same pins control more than one multiplexer. + +Required properties: +- compatible : "gpio-mux" +- mux-gpios : list of gpios used to control the multiplexer, least + significant bit first. +- #mux-control-cells : <0> +* Standard mux-controller bindings as decribed in mux-controller.txt + +Optional properties: +- idle-state : if present, the state the mux will have when idle. The + special state MUX_IDLE_AS_IS is the default. + +The multiplexer state is defined as the number represented by the +multiplexer GPIO pins, where the first pin is the least significant +bit. An active pin is a binary 1, an inactive pin is a binary 0. + +Example: + + mux: mux-controller { + compatible = "gpio-mux"; + #mux-control-cells = <0>; + + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, + <&pioA 1 GPIO_ACTIVE_HIGH>; + }; + + adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&mux>; + + channels = "sync-1", "in", "out", "sync-2"; + }; + + i2c-mux { + compatible = "i2c-mux"; + i2c-parent = <&i2c1>; + + mux-controls = <&mux>; + + #address-cells = <1>; + #size-cells = <0>; + + i2c@0 { + reg = <0>; + #address-cells = <1>; + #size-cells = <0>; + + ssd1307: oled@3c { + /* ... */ + }; + }; + + i2c@3 { + reg = <3>; + #address-cells = <1>; + #size-cells = <0>; + + pca9555: pca9555@20 { + /* ... */ + }; + }; + }; diff --git a/Documentation/devicetree/bindings/mux/mux-controller.txt b/Documentation/devicetree/bindings/mux/mux-controller.txt new file mode 100644 index 000000000000..4f47e4bd2fa0 --- /dev/null +++ b/Documentation/devicetree/bindings/mux/mux-controller.txt @@ -0,0 +1,157 @@ +Common multiplexer controller bindings +====================================== + +A multiplexer (or mux) controller will have one, or several, consumer devices +that uses the mux controller. Thus, a mux controller can possibly control +several parallel multiplexers. Presumably there will be at least one +multiplexer needed by each consumer, but a single mux controller can of course +control several multiplexers for a single consumer. + +A mux controller provides a number of states to its consumers, and the state +space is a simple zero-based enumeration. I.e. 0-1 for a 2-way multiplexer, +0-7 for an 8-way multiplexer, etc. + + +Consumers +--------- + +Mux controller consumers should specify a list of mux controllers that they +want to use with a property containing a 'mux-ctrl-list': + + mux-ctrl-list ::= <single-mux-ctrl> [mux-ctrl-list] + single-mux-ctrl ::= <mux-ctrl-phandle> [mux-ctrl-specifier] + mux-ctrl-phandle : phandle to mux controller node + mux-ctrl-specifier : array of #mux-control-cells specifying the + given mux controller (controller specific) + +Mux controller properties should be named "mux-controls". The exact meaning of +each mux controller property must be documented in the device tree binding for +each consumer. An optional property "mux-control-names" may contain a list of +strings to label each of the mux controllers listed in the "mux-controls" +property. + +Drivers for devices that use more than a single mux controller can use the +"mux-control-names" property to map the name of the requested mux controller +to an index into the list given by the "mux-controls" property. + +mux-ctrl-specifier typically encodes the chip-relative mux controller number. +If the mux controller chip only provides a single mux controller, the +mux-ctrl-specifier can typically be left out. + +Example: + + /* One consumer of a 2-way mux controller (one GPIO-line) */ + mux: mux-controller { + compatible = "gpio-mux"; + #mux-control-cells = <0>; + + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>; + }; + + adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&mux>; + mux-control-names = "adc"; + + channels = "sync", "in"; + }; + +Note that in the example above, specifying the "mux-control-names" is redundant +because there is only one mux controller in the list. However, if the driver +for the consumer node in fact asks for a named mux controller, that name is of +course still required. + + /* + * Two consumers (one for an ADC line and one for an i2c bus) of + * parallel 4-way multiplexers controlled by the same two GPIO-lines. + */ + mux: mux-controller { + compatible = "gpio-mux"; + #mux-control-cells = <0>; + + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, + <&pioA 1 GPIO_ACTIVE_HIGH>; + }; + + adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&mux>; + + channels = "sync-1", "in", "out", "sync-2"; + }; + + i2c-mux { + compatible = "i2c-mux"; + i2c-parent = <&i2c1>; + + mux-controls = <&mux>; + + #address-cells = <1>; + #size-cells = <0>; + + i2c@0 { + reg = <0>; + #address-cells = <1>; + #size-cells = <0>; + + ssd1307: oled@3c { + /* ... */ + }; + }; + + i2c@3 { + reg = <3>; + #address-cells = <1>; + #size-cells = <0>; + + pca9555: pca9555@20 { + /* ... */ + }; + }; + }; + + +Mux controller nodes +-------------------- + +Mux controller nodes must specify the number of cells used for the +specifier using the '#mux-control-cells' property. + +Optionally, mux controller nodes can also specify the state the mux should +have when it is idle. The idle-state property is used for this. If the +idle-state is not present, the mux controller is typically left as is when +it is idle. For multiplexer chips that expose several mux controllers, the +idle-state property is an array with one idle state for each mux controller. + +The special value (-1) may be used to indicate that the mux should be left +as is when it is idle. This is the default, but can still be useful for +mux controller chips with more than one mux controller, particularly when +there is a need to "step past" a mux controller and set some other idle +state for a mux controller with a higher index. + +Some mux controllers have the ability to disconnect the input/output of the +multiplexer. Using this disconnected high-impedance state as the idle state +is indicated with idle state (-2). + +These constants are available in + + #include <dt-bindings/mux/mux.h> + +as MUX_IDLE_AS_IS (-1) and MUX_IDLE_DISCONNECT (-2). + +An example mux controller node look like this (the adg972a chip is a triple +4-way multiplexer): + + mux: mux-controller@50 { + compatible = "adi,adg792a"; + reg = <0x50>; + #mux-control-cells = <1>; + + idle-state = <MUX_IDLE_DISCONNECT MUX_IDLE_AS_IS 2>; + }; diff --git a/MAINTAINERS b/MAINTAINERS index 9e984645c4b0..b2cc32caabb9 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8716,6 +8716,12 @@ S: Orphan F: drivers/mmc/host/mmc_spi.c F: include/linux/spi/mmc_spi.h +MULTIPLEXER SUBSYSTEM +M: Peter Rosin <peda@axentia.se> +S: Maintained +F: Documentation/devicetree/bindings/mux/ +F: include/linux/dt-bindings/mux/ + MULTISOUND SOUND DRIVER M: Andrew Veliath <andrewtv@usa.net> S: Maintained diff --git a/include/dt-bindings/mux/mux.h b/include/dt-bindings/mux/mux.h new file mode 100644 index 000000000000..c8e855c4a609 --- /dev/null +++ b/include/dt-bindings/mux/mux.h @@ -0,0 +1,16 @@ +/* + * This header provides constants for most Multiplexer bindings. + * + * Most Multiplexer bindings specify an idle state. In most cases, the + * the multiplexer can be left as is when idle, and in some cases it can + * disconnect the input/output and leave the multiplexer in a high + * impedance state. + */ + +#ifndef _DT_BINDINGS_MUX_MUX_H +#define _DT_BINDINGS_MUX_MUX_H + +#define MUX_IDLE_AS_IS (-1) +#define MUX_IDLE_DISCONNECT (-2) + +#endif |